Radioimmunoassay of vasopressin during pregnancy. Use and removal of cystylaminopeptidase inhibitors

This paper describes a radioimmunoassay (RIA) for arginine-vasopressin in which o-phenanthroline effectively inhibits cystyl-amino-peptidase activity in whole blood and plasma from pregnant women but in which o-phenanthroline is removed during the extraction of vasopressin from plasma to prevent disturbance of the RIA. Cystyl-amino-peptidase causes immediate degradation of vasopressin unless cystyl-amino-peptidase enzyme inhibitors such as o-phenanthroline are applied. However, o-phenanthroline interferes with RIA. We report an extraction procedure over octadecasyl silica-packed Sep-Pak C18 columns, by which cystyl-amino-peptidase as well as most of the cystyl-amino-peptidase inhibitor is removed from plasma with chloroform. The average o-phenanthroline concentration (0.25 mmol/l) found in the assay medium after extraction appeared not to interfere with the RIA. Polyacrylamide gel isoelectric focusing of extracts of platelet-rich and platelet-poor plasma from pregnant women revealed a single vasopressin immunoreactive peak in the RIA. Recovery and between-assay coefficients of variation of 3.2 ng/l vasopressin from pregnancy whole blood were comparable with non-pregnant controls (57%/8% and 59%/13%, respectively). Results with this assay compare well with those of another assay using inhibitors in pregnant subjects and with results in non-pregnant subjects.     

Prenatal development of the Brattleboro rat is influenced by genotype and lysine vasopressin treatment of the mother

Homozygous (Hom) Brattleboro rats suffer from severe diabetes insipidus (DI) as a consequence of the lack of arginine-vasopressin (AVP) in the brain. Compared with heterozygous (Het) AVP-synthesizing Brattleboro rats, Hom rats show disturbed body and brain development. In this study breeding experiments with Het and Hom rats were performed to determine whether prenatal conditions might contribute to the developmental disturbances in Hom pups. For this purpose Het and Hom females were mated with Hom and Het males, respectively. In addition lysine-vasopressin (LVP) was administered to half of the pregnant females, since this has previously been shown to stimulate birth weight of Hom pups. On day 1 postnatally the body and brain weight of Hom pups of nontreated Hom mothers was significantly smaller than that of the Het litter mates, whereas no difference was found between the weight of Het or Hom pups of nontreated or LVP-treated Het mothers. These results indicate an important role of the genotype of the mother in prenatal development of Hom pups. LVP administration failed to diminish the growth deficits, but increased protein and DNA content of the cerebellum of both Het and Hom pups. Notwithstanding the improved prenatal growth of Hom pups from Het mothers, postnatally retarded development was still observed: at 1 month of age there was a significant difference between the body, brain and cerebellar weight of Het and Hom pups from Het mothers. It was therefore concluded that the prenatal situation of the Hom mother, i.e. AVP-deficiency, significantly contributes to the developmental disturbance of the Hom pup, but also that growth impairment is linked to the presence of the mutation in the Hom pups themselves.     

Fatigue,sleep disturbances and circadian rhythm in multiple sclerosis

The aim of this study was to investigate whether fatigue and sleep disturbances in multiple sclerosis (MS) patients might be due to disrupted circadian sleep wake regulation. Actigraphy and a multiple sleep latency test (MSLT) were performed in 16 MS patients with both prominent sleep complaints and fatigue. Actigraphy scores did not differ from control values, whereas sleep onset latency values were altered in subgroups of MS patients. No evidence was found for a generalized circadian disturbance in MS patients.     

Lymphocytic infiltration in the spinal cord of patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating systemic atrophy affecting the upper and lower motor neurons. The etiology is unknown, but one theory of pathogenesis supposes that the motor system is affected by abnormal immune responses. We have studied the prevalence and extent of lymphocytic infiltration, previously reported as a rare finding in the ALS spinal cord. Application of monoclonal antibodies against macrophages, T- and B-cells to spinal cords from 48 ALS patients disclosed a cellular mononuclear infiltrate in 38 specimens (79%), intense enough to be revealed by routine neuropathological techniques in 6 of them (12.5%); the remaining 10 cords (21%) exhibited no infiltrates. Since duration and clinical signs of the preceeding illness were the same in cases with and without infiltrates, we consider it unlikely that such infiltrates are entirely secondary to atrophy of the cord. As Wallerian degeneration is not accompanied by infiltrates of lymphocytes, their presence in the cord tracts of our material throws doubt on the conventional view that tract degeneration in ALS is exclusively Wallerian.     

Pancreas divisum: thin-section CT

Twelve patients with known pancreas divisum underwent thin-section computed tomography (CT) to determine the capability of CT to depict this pancreatic anomaly. Focal pancreatic enlargement was present in five patients. Two distinct pancreatic moieties separated by a fat cleft were noted in three patients; a fourth patient had focal atrophy in the distribution of the dorsal pancreas. The two pancreatic moieties were identified at the same craniocaudal level in all four of these patients. The dorsal duct was depicted in all 12 patients, while the short ventral duct was seen in only five of the 12 patients. Failure of the ventral and dorsal pancreatic ducts to fuse was identified in all five patients in whom both ducts were seen. CT may not enable specific diagnosis of pancreas divisum in the majority of patients. If, however, distinct pancreatic moieties or unfused ductal systems are evident, the diagnosis may be confidently suggested.     

Stimulation of intra-uterine growth in rat by alpha-melanocyte-stimulating hormone.

We have studied whether endogenous alpha-MSH has a function in stimulating intra-uterine growth in the rat. The approach used was to determine whether or not this hormone is present during the intra-uterine growth spurt, and if binding of endogenous foetal alpha-MSH by antibodies would inhibit this growth. Antibodies against alpha-MSH or ACTH 1-24, either purified or non-purified, induced immunofluorescence in the intermediate lobe of adult male control rats. Using purified anti-alpha-MSH, fluorescence appeared in the foetal intermediate lobe on day 18 of pregnancy, the day that biologically active MSH was first seen. A negative correlation was observed between the pituitary MSH content and foetal body weight only on day 19 of pregnancy. Injection of purified anti-alpha-MSH induced a drop in foetal body weight, but no effect on placental weight was observed. Purified anti-acth 1-24 had no effect upon body weight but caused an increase in placental weight. These results support our previous findings and indicate that endogenous MSH has a function in the stimulation of foetal growth.